The present invention is in the field of environmental protection equipment and is more specifically directed to a new and unique device for entrapping the effluent being discharged from a damaged or inoperative underwater oilwell to permit the recovery of the effluent for subsequent processing so as to minimize environmental pollution and the attendant damage resultant therefrom.
Underwater oilwells have become more and more widely employed throughout the world in recent years and it is an unfortunate fact that malfunctions or damage to such wells can result in the discharge of crude oil into the body of water in which such wells are located. The resultant damage from such discharge of crude oil can amount to many millions of dollars as is well known. These facts have resulted in a variety of approaches for preventing such undesirable discharge of crude oil. For example, all underwater wells are provided with expensive and sophisticated blowout preventer equipment. However, such equipment does not always function properly as evidenced by the 1979 blowout of Mexico's Pemex Ixtoc 1 well in the Gulf of Mexico.
After a blowout occurs, it is imperative that corrective measures be taken as soon as possible in an effort to terminate the discharge of effluent from the well. However, such procedures sometimes requires extremely time-consuming procedures lasting several months such as the drilling of offset wells to intersect the blowout well with the damage from the blowout continuing unabated until shut-off is finally effected. There has consequently been a great need for apparatus for reducing the damage and loss of crude oil during the time that a permanent cutoff is being effected. For example, a large inverted funnel having a forty foot diameter was lowered by cable over the Ixtoc 1 well in an effort to entrap the discharge from the well with the funnel being suspended by cables from a supporting vessel. A hose from the funnel was connected to separation equipment on the surface with it being the intention to discharge the oil into tankers. Unfortunately, this inverted funnel system, which weighed approximately 310 tons exerted a great resistance to movement by virtue of its substantial mass and its geometry which creates substantial water resistance so that vertical movement of the support vessel is resisted by the inverted funnel to create extremely high forces on the supporting cable structure. Consequently, wave action on the supporting vessel rsulted in undue stress and mechanical failure of the supporting structure and the use of the device had to be terminated and abandoned.
Another problem with oil entrapment devices which are supported by cables is that the supporting vessel must necessarily be in the area above the blowout which may well be on fire or which at least presents a substantial hazard of fire. Consequently, it has been recognized that such cable suspended entrapment devices do not provide a satisfactory solution to the problem of recovering the discharged effluent from an underwater blowout. A description of the entrapment equipment employed in the Ixtoc 1 well blowout is found in the May 1980 issue of "Popular Mechanics".
Therefore, it is the primary object of this invention to provide a new and improved effluent entrapment means for underwater oilwell blowouts.
Obtainment of the object of the invention is achieved by the preferred embodiment through the employment of a submergeable vehicle which can be trailed behind and towed by a surface vessel and which has buoyancy adjustment means for effecting raising or lowering of the vehicle to vertically position it with respect to an underwater blowout. More specifically, the vehicle includes a hollow effluent entrapment shell member of generally conical configuration which is open at the bottom and is of sufficient dimensions as to be positioned in a cap-like manner over an underwater well. The effluent entrapment shell is connected to a vertically extending main spinal tube which communicates on its lower end with the upper portion of the interior of the shell and extends vertically thereabove with a plurality of radial outflow tubes being connected to the spinal tube at a substantial distance above the effluent entrapment shell. Additionally, canted brace tubes are also connected to the main spinal tube on their lower ends at a location adjacent the effluent entrapment shell and on their upper ends to the radial outflow tube members. The radial outflow tubes and the spinal tube are connected by hose means to floating separation equipment provided on a barge or the like on the surface of the body of water in which the well is located with a plurality of buoyancy tank members being coaxially mounted on and around the spinal tube, the radial outflow tubes and the canted brace tubes. Air lines extend to the surface for providing compressed air to the buoyancy tanks so as to permit the expelling of the water in the tanks through outlet openings adjacent the bottom of the tanks so as to provide for a desired buoyancy for the entire vehicle.
In use, the preferred embodimet is towed into position above the blowout and the air in the buoyancy tanks is permitted to escape so as to cause the entire device to settle slowly downwardly over the blowout to entrap the effluent therefrom. The effluent is consequently discharged outwardly through the hose means to the separator means on the surface with it being possible to trap substantially all of the effluent so as to minimize environmental and economic damage.
A better understanding of the construction and operation of the preferred embodiment will be achieved when the following detailed description is considered in conjunction with the appended drawings in which like reference numerals are used for the same parts as viewed in the different figures.